Porous inorganic solids have found great utility as catalysts and separation media for industrial application. In particular, mesoporous materials, such as silicas and aluminas, having a periodic arrangement of mesopores are attractive materials for use in catalysis processes due to their uniform and tunable pores, high surface areas and large pore volumes. Such mesoporous materials are known to have large specific surface areas (e.g., 1000 m2/g) and large pore volumes (e.g., 1 cm3/g). For these reasons, such mesoporous materials enable reactive catalysts.
Mesoporous organosilica materials are conventionally formed by the self-assembly of the silsesquioxane precursor in the presence of a structure directing agent, a porogen and/or a framework element. The precursor is hydrolysable and condenses around the structure directing agent. These materials have been referred to as Periodic Mesoporous Organosilicates (PMOs), due to the presence of periodic arrays of parallel aligned mesoscale channels. For example, Landskron, K., et al. [Science, 302:266-269 (2003)] report the self-assembly of 1,1,3,3,5,5-hexaethoxy-1,3,5-trisilacyclohexane [(EtO)2SiCH2]3 in the presence of a base and the structure directing agent, cetyltrimethylammonium bromide, to form PMOs that are bridged organosilicas with a periodic mesoporous framework, which consist of SiO3R or SiO2R2 building blocks, where R is a bridging organic group. In PMOs, the organic groups can be homogenously distributed in the pore walls. U.S. Patent Application Publication No. 2012/0059181 reports the preparation of a crystalline hybrid organic-inorganic silicate formed from 1,1,3,3,5,5-hexaethoxy-1,3,5-trisilacyclohexane in the presence of NaAlO2 and base. U.S. Patent Application Publication No. 2007/003492 reports preparation of a composition formed from 1,1,3,3,5,5-hexaethoxy-1,3,5-trisilacyclohexane in the presence of propylene glycol monomethyl ether.
However, the use of a structure directing agent, such as a surfactant, in the preparation of an organosilica material, requires a complicated, energy intensive process to eliminate the structure directing agent at the end of the preparation process. For example, calcining may be required as well as wastewater disposal steps and associated costs to dispose of the structure directing agent. This limits the ability to scale-up the process for industrial applications. Additionally, because of the relative expense of complex organic-inorganic hybrid siliceous (monomer) materials, it would be beneficial to maintain as many of the structure and properties as possible of a material made from relatively expensive siliceous reactants, while lowering the cost by co-incorporating less expensive reactants, such as silica.
Therefore, there is a need for improved catalysts/adsorbents and/or processes for making catalysts using organosilica materials that can be prepared at as low a cost as possible by methods that can be practiced in the absence of a structure directing agent, porogen, or surfactant.